Coupling Co_(3)[Co(CN)_(6)]_(2) nanocubes with reduced graphene oxide for high-rate and long-cycle-life potassium storage

As one of prussian blue analogues,Co_(3)[Co(CN)_(6)]_(2) has been explored as a promising anode material for potassium-ion batteries(PIBs) owing to its high potassium storage capacity.Unfortunately,Co_(3)[Co(CN)_(6)]_(2) possesses low electronic conductivity and its structure collapses easily during potassiation and depotassiation,resulting in poor rate performance and cyclic stability.To solve these problems,we develop a facile multi-step method to successfully combine uniformCo_(3)[Co(CN)_(6)]_(2) nanocubes with rGO by C-O-Co bonds.As expected,these chemcial bonds shorten the distance betweenCo_(3)[Co(CN)_(6)]_(2) and rGO to the angstrom meter level,which significantly improve the electronic conductivity ofCo_(3)[Co(CN)_(6)]_(2).Besides,the complete encapsulation ofCo_(3)[Co(CN)_(6)]_(2) nanocubes by rGO endows the structure ofCo_(3)[Co(CN)_(6)]_(2) with high stability,thus withstanding repeated insertion/extraction of potassium-ions without visible morphological and structural changes.Benefiting from the abovementioned structural advantages,the CO3 [Co(CN)6]2/rGO nanocomposite exhibits a high reversible capacity of 400.8 mAh g^(-1) at a current density of 0.1 A g^(-1),an exceptional rate capability of 115.5 mAh g^(-1) at 5 A g^(-1), and an ultralong cycle life of 231.9 mAh g^(-1) at 0.1 A g^(-1) after 1000 cycles.Additionally,the effects of different amounts of rGO and different sizes ofCo_(3)[Co(CN)_(6)]_(2) nanocubes on the potassium storage performance are also studied.This work offers an ideal route to significantly enhance the electrochemical properties of prussian blue analogues.

金属硫化物基钾离子电池负极:储存机制和合成策略

钾离子电池由于其低成本和丰富的钾矿产资源,在能量存储和转化领域极具应用潜力。金属硫化物理论容量高且材料种类丰富,在众多钾离子电池负极材料中表现突出。然而,金属硫化物存在的缺点,如导电性差、离子扩散率低、界面/表面传输动力学缓慢等,限制了其在储钾过程中的性能表现。在这篇综述中,我们系统的讨论和总结了金属硫化物作为钾离子电池负极的电化学反应机制、所面临的挑战和合成方法。其中,重点讨论了其常见的合成方法,包括模板法、溶剂热/水热法、固相反应法、静电纺丝法和离子交换法。这篇综述意在通过优化合成策略设计合成理想的组分和结构,来解决钾电负极材料存在的问题,最终得到高性能的钾离子电池负极材料。最后我们还对基于金属硫化物的钾离子电池负极的发展方向进行了展望。

Sn_(4)P_(3)nanoparticles confined in multilayer graphene sheets as a high-performance anode material for potassium-ion batteries

Phosphorus-based anodes are highly promising for potassium-ion batteries(PIBs)because of their large theoretical capacities.Nevertheless,the inferior potassium storage properties caused by the poor electronic conductivity,easy self-aggregation,and huge volumetric changes upon cycling process restrain their practical applications.Now we impregnate Sn_(4)P_(3)nanoparticles within multilayer graphene sheets(Sn_(4)P_(3)/MGS)as the anode material for PIBs,greatly improving its potassium storage performance.Specifically,the graphene sheets can efficiently suppress the aggregation of Sn_(4)P_(3)nanoparticles,enhance the electronic conductivity,and sustain the structural integrity.In addition,plenty of Sn_(4)P_(3)nanoparticles impregnated in MGS offer a large accessible area for the electrolyte,which decreases the diffusion distance for K^(+)and electrons upon K^(+)insertion/extraction,resulting in an improved rate capability.Consequently,the optimized Sn_(4)P_(3)/MGS containing 80 wt%Sn_(4)P_(3)(Sn_(4)P_(3)/MGS-80)exhibits a high reversible capacity of 378.2 and 260.2 m Ah g;at 0.1 and 1 A g^(-1),respectively,and still delivers a large capacity retention of 76.6%after the 1000th cycle at 0.5 A g^(-1).

A universal cooperative assembly-oriented strategy for VS_(4) nanorod decoration on carbon nanostructures with enhanced magnesium storage properties

VS_(4) has a unique layered atomic chain structure and has the potential to become a high-performance cathode material of magnesium-ion batteries with a high capacity and long cycle life.However,low conductivity and sluggish Mg^(2+)diffusivity during cycling limit its practical application in large-scale energy storage.Herein,a cooperative assembly-directed strategy is adopted to synthesize VS_(4) nanorods grown in situ on carbon nanotubes(CNTs/VS_(4)).VS_(4) nanorods are tightly anchored to CNTs through V-O-C interface covalent bonds,and CNTs can enhance the electronic conductivity of the nanocomposite.In addition,the ion insertion reaction using Mg^(2+)and Mg Cl^(+)as carriers reduces the polar barrier for divalent Mg^(2+)ion transport.This rationally designed architecture promotes ion diffusion and electron transfer,thus facilitating reaction kinetics.The cooperative assembly-oriented strategy can endow CNTs/VS_(4) with excellent magnesium storage properties,including a high reversible capacity of 223.2 m Ah g^(-1)at a current density of 50 m A g^(-1),a remarkable discharge capacity of 91.8 m Ah g^(-1)even at 2,000 m A g^(-1),and an impressive capacity retention of 85.2% after 1,000 cycles at 500 m A g^(-1).Moreover,this strategy can serve as a general synthetic method for the complexation of VS_(4) with other carbon nanostructures.

Spatiotemporal variation of cyanobacterial harmful algal blooms in China based on literature and media information

Cyanobacterial harmful algal blooms(CyanoHABs)in inland waters are now among the most pressing environmental issues worldwide,especially in China.Satellite remote sensing has limitations in monitoring CyanoHABs in small water bodies due to spatial and temporal resolution limitations.While literature and news media have the potential to supplement satellite remote sensing in monitoring CyanoHABs,they have currently not received sufficient attention.In this study,we combined information on the distributions of CyanoHABs from literature and media for the first time to comprehensively assess the spatiotemporal variation in CyanoHABs in China.We collected,cleaned,validated,and organized data from literature and media on CyanoHABs in China,resulting in the establishment of a comprehensive database on CyanoHABs in China's inland waters(ChinaCyanoDB)covering 198 water bodies,525 records for 1950-2021.The majority of water bodies with CyanoHABs(CyanoWaters)are located in the eastern China,mainly concentrated in the middle and lower Yangtze region,with a clear upward trend in their number over the last four decades.The ChinaCyanoDB and analytical results can provide valuable data support for monitoring and managing CyanoHABs in China while the database construction method may also be applied to other countries and regions.

Robust carbon nanotube-interwoven KFeSO_(4)F microspheres as reliable potassium cathodes

Orthorhombic iron-based fluorosulfate KFeSO_(4)F represents one of the most promising cathode materials due to its high theoretical capacity,high voltage plateau,unique three-dimensional conduction pathway for potassium ions,and low cost.Yet,the poor thermostability and intrinsic low electronic conductivity of KFeSO_(4)F challenge its synthesis and electrochemical performance in potassium-ion batteries(PIBs).Herein,we report,for the first time,judicious crafting of carbon nanotubes(CNTs)-interwoven KFeSO_(4)F microspheres in diethylene glycol(DEG)(denoted KFSF@CNTs/DEG)as the cathode to render high-performance PIBs,manifesting an outstanding reversible capacity of 110.9 m Ah g^(-1) at 0.2 C,a high working voltage of 3.73 V,and a long-term capacity retention of 93.9%after 2000 cycles at 3 C.Specifically,KFSF@CNTs/DEG microspheres are created via introducing CNTs into the precursors DEG solution at relatively low temperature.Notably,the strong binding of the ether groups in DEG retards the nucleation and growth of KFSF,leading to in situ formation of microspheres with CNTs interwoven within KFSF crystals,thereby greatly enhancing electronic conductivity of KFSF.Intriguingly,the remarkable electrochemical performance of KFSF@CNTs/DEG cathode is found to stem from the massively exposed(100)plane and uniform interpenetration of CNTs inside KFSF microsphere.More importantly,in situ X-ray diffraction and electrochemical kinetics study unveil outstanding structural stability and high K+diffusion rate of KFSF@CNTs/DEG.Finally,the KFSF@CNTs/DEG//graphite full cell displays a large energy density of~243 Wh kg^(-1).Such simple route to KFSF@CNTs/DEG highlights the robustness of creating inexpensive CNTs-interwoven polyanionic cathodes for high-performance PIBs.

UAV search-and-rescue planning using an adaptive memetic algorithm

The use of unmanned aerial vehicles(UAVs) is becoming more commonplace in search-and-rescue tasks,but UAV search planning can be very complex due to limited response time, large search area, and multiple candidate search modes. In this paper, we present a UAV search planning problem where the search area is divided into a set of subareas and each subarea has a prior probability that the target is present in it. The problem aims to determine the search sequence of the subareas and the search mode for each subarea to maximize the probability of finding the target. We propose an adaptive memetic algorithm that combines a genetic algorithm with a set of local search procedures and dynamically determines which procedure to apply based on the past performance of the procedures measured in fitness improvement and diversity improvement during problem-solving. Computational experiments show that the proposed algorithm exhibits competitive performance compared to a set of state-of-the-art global search heuristics, non-adaptive memetic algorithms, and adaptive memetic algorithms on a wide set of problem instances.

Double-Coated Fe_(2)N@TiO_(2)@C Yolk-Shell Submicrocubes as an Advanced Anode for Potassium-Ion Batteries

Main observation and conclusion Rationally designing inexpensive iron nitrides that have large conductivity,high theoretical capacity,and rapid ionic diffusion kinetics is of great importance for realizing their practical application in potassium-ion batteries.